Certificate of correction



Reiuued Feb. '14, 1933 UNITED STATES PATENT OFFICE.

OARLISLE K. 3005, OF WHEATON, ILLINOIS, ASSIGNOB TO UNITED STATES GYPSUI- COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS ACOUSTIC PLAB'IEB Ho Drawing. Original No. 1,871,806, dated August 16, 1982, Serial 11,0. 186,600, fled I ebruary 7, 1927.

Application for reissue filed October 18,1932. Serial No. 838,414.

This invention relates to building material but more particularly to a special plaster which may be applied to walls or ceilings by means of ordinary plastering tools and which when so applied has the property of absorbing sound to a greater degree than ordinary wall plasters.

Heretofore it has not been found practical to produce sound absorbin could be applied by the ordinary plastering tools using calcined gypsum as the cementitious base. The gypsum used has been the well known plaster of Paris, calcined at 330 degrees Fahrenheit and commonly known as first settle stucco. This product is the most plastic of all the commercial forms of calcined gypsum and accordingly has been used as a base for all gypsum wall plasters. Due to its high plasticity it will work plastic with high addltions of aggregate and large amount of water for gauging purposes. When sufiicient quantities of the aggregates have been used with this type of cementitious base, sufficient to form a cellular sound absorbing wall plaster, the resultant product has lacked the strength and hardness necessar for a good wall finish. I

t is the object of this invention to produce a sound absorbing wall plaster which can be readily applied to walls or ceilings by the ordinary plastering tools using calcined gypsum as the cementitious base.

It has been found that a special calcined gypsum or aridized stucco (made according to Brookby Patent No. 1,370,581) is particularly well adapted to use as a base for sound absorbing plaster, giving a gypsum sound absorbing wall plaster of proper porosity and strength. This calcined gypsum is well suited for the reason that it is much less plastic, requires less water for mixing and has about twice the strengthof the usual first settle calcined gypsum; While this special calcined gypsum is preferred, other calcined gypsum bases may be used. These are the low consistency gypsum plasters such as Keenes cement, second settle calcined gypsum and first settle calcined gypsum aged in storage for a period of several months.

The production of acoustic plaster by this plaster which.

method entails only the dry mixing, in the ordinary plaster mixer, of the calcined gypsum together with the aggregate and an air entraining agent. The best results have been obtained using the following formulae:

v Formula N o. 1 i No. 5 stucc0 500 pounds No. 4 quartz silica 250 pounds. No. 7 quartz silica 250'pounds Mixed pumice 600 pounds Retarder 1 pound 8 ounces Powdered soap bark 9 ounces Fomula No, 2 No. 5 stucco 500 pounds Mixed pumice 550-600 pounds Crushed marble 500 pounds Retarder -1. 20 ounces Powdered soap bark 8 ounces The No. 5 stucco is air separated calcined psum made according to the Brookby Patent #1,37 0,581; the No. 4 quartzsilica a non-porous aggregate weighing approximately 84 pounds per cubic foot-having a sieve analysis of 18% on 20 mesh, 95% on 30 mesh and 99.5% on 40 mesh; the N0. 7 quartz silica weighs approximately 87 pounds per cubic foot and is crushed to .asize testing 5% on a 10 mesh and-99% on 20 mesh; the mixed pumice weighs about-40 pounds per cubic foot and has a sieve analysis of 1% on 10 mesh, 31% on 20 mesh, 70% on 30 mesh and 98% on 100 mesh. 1

Other grades of quartz or pumice may beused, such as No. 5 quartz with an average screen analysis of 1% on 10 mesh, 60% on 20 mesh and100% on 30 mesh. The coarser aggregate not necessarily closely graded may be used. These need not have sharp projecting points and may be round, but if round they should be graded nearly to one size in order to obtain minimum cubical pilin (see Bancroft Applied Colloid Chemistry It is preferable that a part of the aggregate be pumice since its use gives a lighter weight mortar mix which will cover greater yardage in the plastering operation. However it maybe omitted and quartz used entirely, in

which case five parts ofqu-artz aggregate would be used to. one part of calcined gypsum. The quartz or t e umice may be replaced by quartzites, eldspar nister, crushed marble and similar materials; A porous aggregate is not necessary for sound absorption providing the cementitious matrix surrounding the aggregate is porous or cellular. The ideal size for any aggregate is one that will retained on a 28 mesh screen. To produce a cellular structure within th cementitious matrix, a gas entrainer is used, preferably a non-retarding gas entrainer. Among those which may be used are those of tht saponaceous variety such as ground soap bark, soapberry Yucca roots, Sapendis nuts or saponin itsel v The bubbles are formed throughout the mortar by'the air contained in and on the surface of the particles of'calcined gypsum and form the surfaceair film on the particles of the aggregate. The wetting of the plaster in making up the mortar liberates the air occluded in the calcined gypsum and on the surface of the a gregate.- This air is entrained by any 0 the entrainers mentioned above and forms a light working cellular mortar which on hardening leaves, a cellular structure between the aggregate. The surface film of the bubble having saponin on the intor-face is very tenacious and withstands the l abrasion of the aggregate. For this reason excessive mixing of the mortar does not cause them to coalesce, but simply breaks them up into a finer cell structure without appreciably im the plaster sound absorbin value.

plaster made according to,the ormula given above has been tested and shows an average *abs'o tion coeflicient of for the octave C to ,,'while the coeflicient is to rcent for the octave C, to C 'l iiis plaster is sufficiently plastic to be applied in a manner similar to any other wall plaster. Ordinarily a scratch coat of ordinary plaster is apphed to the lath, over which is applied two coats 'of acoustic plaster. The

second'is agplied with a cork float to produce a finis and a mu h pitted surface. Having thus describe Iclaimis: 1

' 1. A plastic sound-absorbing wall plaster capable of application by troweling and setto a porous mass consisting of a mixture of calcined gypsum, water, a graded nonporous aggregate, a graded porous aggregate, 'a foaming agent ofthe saponin t pe and acommercial gypsum-setting retar er.

2. A plastlc sound-absorbing wall' plaster capable of application by troweling and setting to a porous mass consisting of a mixture of calcined gypsum, water, graded crushed marble, graded crushedv pumice, a foaming agent 0 the saponin type and a commercial gysum-setting retarder.

3. A dry mix compositlon that on gaging pass a14 mesh screen and be granulate my invention, what with water forms a plastic mortar capable of with water forms a p astic mortar capable 0 application by troweling to walls, ceilings and the like, and which sets to form an acoustic sound-absorbing plaster surface, consist ing of'commercial retarded gypsum stucco, g giadedsized aggregate and powdered soap 5. A dry mix composition that on ga -ng with water forms a plaster mortar capab e of application by troweling to walls, ceilings and the like and which sets to form an acoustic sound-absorbing plaster surface, consisting of commercial retarded gypsum stucco, a graded ag egate of granulated pumice and marble, and a foam-producing agent of the saponin type capable of entrap- .p1ng air bubbles.

6. A dry mix composition thaton gaging with water forms a plastic mortar capable of application by troweling to walls, ceilings and the like and which sets to form an acoustic sound-absorbing plaster surface, consisting of commercial retarded gypsum stucco, a graded aggregate of granulated pumice and granulate marble, and'powdered soap bark. I 7. A dry. mix composition that on gagin with water forms a plastic mortar capable 0 application by troweling to walls, ceilin an the like and which sets to form an acoustic sound-absorbing plaster surface, consisting. of commercial retarded g psum stucco, a

graded aggregate of gran ated marble and umice sized between 14 and 28 mesh, and a I 0am.- roducing'agent of-the saponin type capab eof entrapping air bubbles.

8. A dry mix composition that on gaging with water forms a plastic mortar ca able of application by troweling to walls, ce' ings andthe like and which sets to form an acoustic sound-absorbing plaster surface, consisting of commercialretarded gy sum stucco, a graded aggregate of granulated marble and powdered soap bark.

9. A dry mix composition that on gaging with'waterforms a plastic.'mortar capable of application by troweling to walls, ceilings pumice sized between 14 and-28, mesh, and a Y composition consisting of commercial retarded psum stucco, a graded sized aggregate,

an a foam-producing agent of the saponin 5 type cable of entrapping air bubbles.

11.'An acoustic sound-absorbing plaster resulting from the setting of a water-gaged composition consisting of commercial retarded gypsum stucco, a graded sized aggregate,

and powdered soap bark.

12. An acoustic sound-absorbing plaster resulting from the setting of a water-gaged composition consisting of commercial ret arded gypsum stucco, a aded aggregate of 5 granulated pumice an granulated marble, type capable of entrapping air bubbles. j

13. An acoustic sound absorbing plaster resulting from the setting of a water-gaged 0 ed gypsums'tucco, a graded aggregate of granulated pumice and granulated marblei and powdered soap bark.

14. An acoustic sound-absorbing plaster resulting from the setting of a water-gaged composition consisting of commercial retarded gypsum stucco, a graded aggregate of granulated marble and pumice sized between 14 and 28 mesh; and a foam-producing agent of the saponin type capable of entrapping air bubbles. a

15. An acoustic sound-absorbing plaster resulting from the setting of a water-gaged composition consisting of commercial retard ed gypsum stucco, a graded aggregate of granulated marble and pumicesized between 14 and 28 mesh, and powdered soap bark,

' 16. An acoustic sound-absorbing plaster resulting from the setting of a water-gaged parts of gypsumstucco', 550-600 parts of granulated pumice, 500 parts of granulated marble, 1% parts of commercial retarder, and part of powdered soap bark.

17. A dry mix com osition that on gaging with water forms a p astic mortar capable of application by troweling to walls, ceilings and the like and which sets to form an acoustic sound-absorbing plaster surface, comprising a minor quantlty of an aged low-consistency calcined gypsum base, a .maj or quantity of a graded sized aggregate, and a small quantity of a foam-producingagent of the saponin type capable of entrapping air bub- 18. A dry mix composition that on gaging with water forms a plastic mortar capable of application by troweling to walls, ceilings and the like, and which sets to form an acoustic sound-absorbing plaster surface, comprisency calcined gypsum base, a major quantity of a graded sized aggregate and a small quantity of powdered soap bark.

4 with water forms a plastic mortar capable and a foam-producing agent of the saponin composition consisting of commercial retard-' composition consisting of substantially 500 ing a minor quantity of an aged low-consist of application by'troweling to walls, ceilings and the like and which sets to form an acoustic sound-absorbing plaster surface, comprising a minor quantity of an artificially preaged low-consistency calcined gypsum base,

amaj or quantity of a graded sized aggregate, and a small quantity of a' foam-producing agent of the saponin type capable of entrap- .ping air bubbles. l

20. A dry mix composition that on gaging aged" low-consistency calcined gypsum base,

a majorquantity of a graded sized aggregate and asmall quantity of powdered soap bark.

21. An acoustic sound-absorbing plaster resulting from the setting of a water-gaged composition comprising a minor quantity of an aged low-consistency calcined gypsum base, a major quantity of a graded sized aggre ate, and a small quantity of a foam-producmg agent of the saponin type capable of entrapping air bubbles.

22. An acoustic sound-absorbing plaster resulting from the setting of a water-gaged composition comprising a minor quantity of an aged low-consistency calcined gypsum base, a major quantity of a gregate, and a small quantity of powdered soap bark.

23. An acoustic sound-absorbing plaster resulting from the setting of a water-gaged composition comprisin a minor quantity of an artificially pre-age low-consistency calcined gypsum base, a major quantity of a graded sized aggregate, and a small quantity of a foam-producing agent of the saponin v type capable of entrapping air bubbles.

24. An acoustic sound-absorbing plaster graded sized agresulting from the'setting oi awater-gaged I composition comprising a minor quantity of an artificially pr'e-aged low-consistency cal cined gypsum base, a major quantity of a. graded sized aggregate, and a small quantity of powdered soa bark.

25. Asound-a sorbingwall plaster composition comprising' calcined gypsum, a

graded sized aggregate, and a foaming agent of the saponin type, the ratio by weight of aggregate to calcined gypsum being at least 2- 1 her, 1932. 19. A dry mix composition that on gaging CARLISLE K. ROOS.

CERTIFICATE OF CORRECTION.

mm No. 18,139, February 14, 1933.

CARLISLE K.. 1100s.

It isherehy certified that error appears in the-printed specification of the 7 above numbered patentjrequiring correction as follows; Page 2, line 83, claim 5, for "plaster" read "plastic"; page 3, line 4, cl-aini'lO, for "cable" read "capable"; and that the said Letters Patent should be readwith these corrections therein that the same may conform -'to therecord otthe case in the-Patent Office.

Signed and-sealed this 9th day of May, A. D. 1933.

(Seal) 1 Q ActinfGMfinf'fssQkPJf'of Patents. 

